Back
TechnicalBike

Bicycle brake fluid: Shimano mineral vs DOT — don't mix them up

M
Max
4 minApril 26, 2026
Bicycle brake fluid: Shimano mineral vs DOT — don't mix them up

Two incompatible worlds

Two types of hydraulic brake fluid exist for bicycles, and they are completely incompatible:

TypeBrandsChemical base
Mineral oilShimano, Magura, TektroParaffin oil
DOT (4 or 5.1)SRAM, Hope, Hayes, FormulaPolyethylene glycol

Why you NEVER mix them

Seals are made from materials specific to each fluid type:

  • DOT in a Shimano brake: seals swell and disintegrate within 24-48 hours
  • Mineral oil in a SRAM brake: same catastrophic failure
The specialised AI mechanic

Ask the AI mechanic your real question

Share your exact model, get the sourced answer in seconds.

L'Atelier Assistant

Source: Official workshop manuals

Ask the AI mechanic…

How to identify your system

  • Shimano (Deore, SLX, XT, XTR, 105, Ultegra) → MINERAL
  • Magura (MT5, MT7, MT8) → MINERAL
  • SRAM / Avid (Guide, Code, Level, G2) → DOT 5.1
  • Hope (Tech 3, Tech 4) → DOT 5.1
  • Hayes, Formula → DOT 4

DOT 4 vs DOT 5.1

Both are compatible and mixable. DOT 5.1 has higher boiling point (270C vs 230C dry). You can use 5.1 in a system designed for 4.

WARNING: DOT 5 (silicone-based) is NOT the same as DOT 5.1 (glycol). Never use DOT 5.

For the complete step-by-step bleeding procedure, check our Shimano brake bleeding guide.

Not sure which fluid your brakes need? Ask L'Atelier — it knows every Shimano and SRAM reference.

Not sure which to pick? Ask the AI

Compatibility, equivalents, alternatives — tailored to your machine.